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March 17, 2011

Lasers, Telescope Optics Could Solve Space Junk Problem

by Sam Savage

The problem of space junk floating around Earth, which could one day force nations to cancel interstellar missions, could be solved using ground-based lasers, claims a new report prepared by NASA-affiliated scientists.

According to Stuart Gary of ABC News Australia, there are currently more than 19,000 objects at least 10cm in size orbiting our planet, while Charles Cooper of CBS News reports that NASA estimates that the total number of debris surrounding the planet tops the 500,000 mark, with some of them achieving top speeds in excess of 17,500mph.

The issue, says Daniel Bates of the Daily Mail, has officials worrying about a phenomenon known as the Kessler Syndrome, in which there would be too much space junk orbiting Earth for anyone to fly into space, thus leaving us trapped on our own planet.

According to Bates, NASA has been predicting such an occurrence for over three decades, and "a string of recent near-misses have added urgency to the need to find a solution."

As a result, a team of researchers from NASA's Ames Research Center and the Universities Space Research Association (USRA) have completed a paper in which they argue that commercially available lasers and telescope technology could develop a beam, slightly more powerful than the sun's rays, which would force the debris to change its orbit.

"The idea would center around the deployment of a medium-powered laser of 5 to 10 kilowatts to essentially nudge debris off potential collision course," said Cooper, who notes that research team leader James Mason and colleagues "argue that such a system is feasible."

"Although they say more study is required before actual implementation of a laser collision avoidance system, they report that lab simulations suggest that the idea would work in practice," the CBS News reporter added.

Mason told Gary that the physics behind their proposed laser were "the same as using the light pressure of photons to propel solar sails through space, and would be a fraction of the cost of physically collecting disused equipment and debris in orbit."

He added that by combining a five-kilowatt laser like the kind usually used for industrial welding with "adaptive optics" typically used on powerful telescopes, a beam could be produced that would, over the course of a few days, "provide enough momentum to move objects sufficiently to avoid a significant proportion of predicted collisions."

"We aren't trying to deorbit objects, just prevent collisions," he added. "To actually deorbit a target would require a thousand times more power than we're talking about."